Research progress on early diagnostic biomarkers and liquid biopsy technologies for colorectal cancer: a comprehensive review

Colorectal cancer (CRC) remains one of the most prevalent and lethal malignancies globally, with its prognosis heavily dependent on the stage at diagnosis. Early detection (stages 0-I) significantly improves 5-year survival rates to over 90%, whereas advanced stages (III-IV) are associated with survival rates below 15%. However, current clinical screening tools (e.g., colonoscopy, fecal occult blood test) suffer from limitations such as invasiveness, poor patient compliance, or low sensitivity for early lesions. In recent years, liquid biopsy, characterized by non-invasiveness, real-time monitoring, and multi-analyte detection, has emerged as a promising strategy for CRC early diagnosis. This review systematically summarizes the latest advances in CRC early diagnostic biomarkers (including circulating tumor DNA, circulating tumor cells, extracellular vesicles, and protein/microbial markers) and corresponding liquid biopsy technologies. We critically discuss the clinical performance, advantages, limitations, and challenges of each biomarker/technology, evaluate evidence quality and field maturity, and provide perspectives on mechanistic insights and future directions for translating these innovations into clinical practice.